Sensitive Ground Relaying of A-C Generators [includes discussion]

Increased use has been made recently of high resistance neutral grounding of generators which operate in unit connection on high-voltage bus bars. High resistance grounding is achieved by connecting a constant resistance between the secondaries of a distribution transformer, the primaries of which are connected to the generator neutral and to ground. Replacing this resistance by one of nonlinear characteristic improves the protection by reducing the dead zone. Ground protection of the complete winding, including the neutral, may be achieved by introducing permanent neutral displacement by means of a small distribution transformer.